Diastereoselective construction of tetracyclic chromanes via a triply annulative strategy.

A triple Michael/aldol cascade reaction has been established to construct tetracyclic chromanes in a diastereoselective fashion (≥5 : 1 dr). The polycyclic products were generated in 50-78% isolated yields under mild and metal-free conditions. Five reactive sites of enolate-tethered divinyl ketones were sequentially utilized to form four C-C bonds in a one-pot operation, leading to a construction of three new rings. Up to six consecutive stereocenters, including two quarternary stereogenic centers, were created in this domino process.

Unexpected rise of atmospheric secondary aerosols from biomass burning during the COVID-19 lockdown period in Hangzhou, China.

After the global outbreak of COVID-19, the Chinese government took many measures to control the spread of the virus. The measures led to a reduction in anthropogenic emissions nationwide. Data from a single particle aerosol mass spectrometer in an eastern Chinese megacity (Hangzhou) before, during, and after the COVID-19 lockdown (5 January to February 29, 2020) was used to understand the effect lockdown had on atmospheric particles. The collected single particle mass spectra were clustered into eight categories. Before the lockdown, the proportions of particles ranked in order of: EC (57.9%) < K-SN (13.6%) < Fe-rich (10.2%) < ECOC (6.7%) < K-Na (6.6%) < OC (3.4%) < K-Pb (1.0%) < K-Al (0.7%). During the lockdown period, the EC and Fe-rich particles decreased by 42.8% and 93.2% compared to before lockdown due to reduced vehicle exhaust and industrial activity. By contrast, the K-SN and K-Na particles containing biomass burning tracers increased by 155.2% and 45.2% during the same time, respectively. During the lockdown, the proportions of particles ranked in order of: K-SN (39.7%) < EC (38.1%) < K-Na (11.0%) < ECOC (7.7%) < OC (1.2%) < K-Pb (0.9%) < Fe-rich (0.8%) < K-Al (0.6%). Back trajectory analysis indicated that both inland (Anhui and Shandong provinces) and marine transported air masses may have contributed to the increase in K-SN and K-Na particles during the lockdown, and that increased number of fugitive combustion points (i.e., household fuel, biomass combustion) was a contributing factor. Therefore, the results imply that regional synergistic control measures on fugitive combustion emissions are needed to ensure good air quality.

Surface tension and viscosity measurement of oscillating droplet using rainbow refractometry.

We extend rainbow refractometry to quantify the oscillations of a droplet in its fundamental mode. The oscillation parameters (frequency and amplitude damping), extracted using the time-resolved rainbow angular shift, are utilized to measure surface tension and viscosity of the liquid. Proof-of-concept experiments on an oscillating droplet stream produced by a monodisperse droplet generator are conducted. Results show that the relative measurement errors of surface tension and viscosity are 1.5% and 8.4% for water and 5.3% and 2.5% for ethanol. This approach provides an alternative mean for characterizing liquid surface properties, e.g., dynamic surface tension and viscosity, especially for liquids with a low Ohnesorge number.

Characterization of a new smog chamber for evaluating SAPRC gas-phase chemical mechanism.

A new state-of-the-art indoor smog chamber facility (CAPS-ZJU) has been constructed and characterized at Zhejiang University, which is designed for chemical mechanism evaluation under well-controlled conditions. A series of characterization experiments were performed to validate the well-established experimental protocols, including temperature variation pattern, light spectrum and equivalent intensity (JNO2), injection and mixing performance, as well as gases and particle wall loss. In addition, based on some characterization experiments, the auxiliary wall mechanism has been setup and examined. Fifty chamber experiments were performed across a broad range of experimental scenarios, and we demonstrated the ability to utilize these chamber data for evaluating SAPRC chemical mechanism. It was found that the SAPRC-11 can well predict the O3 formation and NO oxidation for almost all propene runs, with 6 hr Δ(O3 - NO) model error of -3% ± 7%, while the final O3 was underestimated by ~20% for isoprene experiments. As for toluene and p-xylene experiments, it was confirmed that SAPRC-11 has significant improvement on aromatic chemistry than earlier version of SAPRC-07, although the aromatic decay rate was still underestimated to some extent. The model sensitivity test has been carried out, and the most sensitive parameters identified are the initial concentrations of reactants and the light intensity as well as HONO offgasing rate and O3 wall loss rate. All of which demonstrated that CAPS-ZJU smog chamber could derive high quality experimental data, and could provide insights on chamber studies and chemical mechanism development.

Phase critical angle scattering for measurement of transient nanoscale growth rate of a micron-sized bubble.

We developed phase critical angle scattering (PCAS) to simultaneously measure the spherical and transparent bubble size at the micron scale and transient bubble growth at the nanoscale. The theoretical derivation of PCAS reveals that the phase of the fine structure of critical angle scattering caused by reflection and first-order refraction is highly sensitive to and linearly shifts with bubble diameter growth. Experiments on a single growing bubble are implemented with a Fourier imaging system. The results show that the PCAS technique can measure the tiny bubble growth down to tens of nanometers, providing a promising tool for accurate characterization of bubble dynamics.

Accurate detection of small particles in digital holography using fully convolutional networks.

Particle detection is a key procedure in particle field characterization with digital holography. Due to various background noises, spurious small particles might be generated and real small particles might be lost during particle detection. Therefore, accurate small particle detection remains a challenge in the research of energy and combustion. A deep learning method based on modified fully convolutional networks is proposed to detect small opaque particles (e.g., coal particles) on extended focus images. The model is tested by several experiments and proved to have good small particle detection accuracy.

Characterization of atomization and breakup of acoustically levitated drops with digital holography.

A digital holographic particle tracking velocimetry system is applied to quantitatively study the drop atomization induced by capillary waves, and the breakup caused by increased sound pressure levels. A wavelet-based algorithm is used for particle detection and autofocusing with a wide size range of 20 µm-2 mm. To eliminate the influence of large particles on small particles, a two-step detection method is adopted. Large drops are first characterized and simulated by a diffraction-based model. Then the contributions of the drops are subtracted from the original hologram followed by the detection of small droplets. Finally, the velocity and size distribution of the secondary droplets are obtained from the experimental holograms. The results demonstrate the validity of the digital in-line holographic technique for the atomization and breakup study of acoustically levitated drops.

One-dimensional rainbow thermometry system by using slit apertures.

A new rainbow thermometry system by using slit apertures and a laser light sheet, called a one-dimensional rainbow thermometry (ORT) system, has been developed as an extension of global rainbow thermometry (GRT). This system is capable of one-dimensional or line measurements of the size and refractive index of droplets in the spray space, while the conventional GRT system is normally considered a typical "single-point" or "small volume" measurement method. The performance of this new system was tested and verified with both water and ethanol spray. The results show the feasibility and potential of ORT in simultaneous and one-dimensional measurement of the size and refractive index of liquid droplets, especially in the research field of spray evaporation and combustion.

Blockade of mGluR5 in the nucleus accumbens shell but not core attenuates heroin seeking behavior in rats.

AIM: Glutamatergic neurotransmission in the nucleus accumbens (NAc) is crucial for the relapse to heroin seeking. The aim of this study was to determine whether mGluR5 in the NAc core or shell involved in heroin seeking behavior in rats. METHODS: Male SD rats were self-administered heroin under a fixed-ratio 1 (FR1) reinforcement schedule for 14 d, and subsequently withdrawn for 2 weeks. The selective mGluR5 antagonist 2-methyl-6-phenylethynyl-pyridine (MPEP, 5, 15 and 50 nmol per side) was then microinjected into the NAc core or shell 10 min before a heroin-seeking test induced by context, cues or heroin priming. RESULTS: Microinjection of MPEP into the NAc shell dose-dependently decreased the heroin seeking induced by context, cues or heroin priming. In contrast, microinjection of MPEP into the NAc core did not alter the heroin seeking induced by cues or heroin priming. In addition, microinjection with MPEP (15 nmol per side) in the NAc shell reversed both the percentage of open arms entries (OE%) and the percentage of time spent in open arms (OT%) after heroin withdrawal. Microinjection of MPEP (50 nmol per side) in the striatum as a control location did not affect the heroin seeking behavior. Microinjection of MPEP in the 3 locations did not change the locomotion activities. CONCLUSION: Blockade of mGluR5 in NAc shell in rats specifically suppresses the relapse to heroin-seeking and anxiety-like behavior, suggesting that mGluR5 antagonists may be a potential candidate for the therapy of heroin addiction.

Droplet characteristic measurement in Fourier interferometry imaging and behavior at the rainbow angle.

This paper presents the possibility of measuring the three-dimensional (3D) relative locations and diameters of a set of spherical particles and discusses the behavior of the light recorded around the rainbow angle, an essential step toward refractive index measurements. When a set of particles is illuminated by a pulsed incident wave, the particles act as spherical light wave sources. When the pulse duration is short enough to fix the particle location (typically about 10 ns), interference fringes between these different spherical waves can be recorded. The Fourier transform of the fringes divides the complex fringe systems into a series of spots, with each spot characterizing the interference between a pair of particles. The analyses of these spots (in position and shape) potentially allow the measurement of particle characteristics (3D relative position, particle diameter, and particle refractive index value).

Does industrial up-gradation, environment regulations, and resource allocation impact on foreign direct investment: Empirical evidence from China.

Because of China's tremendous increase in foreign direct investment (FDI) over the past two decades, this method of internationalization has become increasingly significant for companies worldwide. Heavy industry's dominant role in China's industrial structure must be modernized to ensure the country's long-term growth and prosperity. There are 30 provinces in China covered by this dataset, which dates back from 2005 to 2018. Augmented mean group (AMG) and common correlated effects mean groups (CCE-MG) estimations demonstrate that China's industrial upgrading and resource allocation considerably impact FDI inflows. The findings show that FDI inflows appear to be negatively affected by environmental rules. The results show that industrial upgradation and environmental regulations have not had the expected effect on FDI in China without the participation of other stakeholders. For the selected panel, the results from the control variable show that population aging reduces foreign direct investment inflows, whereas, economic growth increases FDI inflows. According to our findings and those of the empirical study, we make some policy proposals to help Chinese provinces attract more foreign direct investment by encouraging and upgrading the screening of such investments.

Dialect diversity and total factor productivity: Evidence from Chinese listed companies.

Using a sample of Chinese listed companies over the 2007-2019 period, we examined the influence of dialect diversity on a firm's total factor productivity. We found that dialect diversity affects the psychological distance of interpersonal communication and significantly affects the firm's total factor productivity. The results are robust to a battery of tests based on different specifications. The relationship between dialect diversity and a firm's total factor productivity is more pronounced in state-owned enterprises, firms located in southern regions, and more capital-intensive firms. Furthermore, we demonstrated an innovative factor flow mechanism and a human capital accumulation mechanism through which dialect diversity inhibits total factor productivity. Overall, this paper provides new evidence and decision-making reference for coordinating the protection of dialect diversity and high-quality economic development.

Measurements of 3D relative locations of particles by Fourier Interferometry Imaging (FII).

In a large number of physical systems formed of discrete particles, a key parameter is the relative distance between the objects, as for example in studies of spray evaporation or droplets micro-explosion. This paper is devoted to the presentation of an approach where the relative 3D location of particles in the control volume is accurately extracted from the interference patterns recorded at two different angles. No reference beam is used and only ten (2 + 8) 2D-FFT have to be computed.

Coal powder measurement by digital holography with expanded measurement area.

The field of view of digital in-line holography for flow field diagnostics is restricted to a small volume due to the finite size and the low spatial resolution of the available CCD. Expansion of the measurement cross section of digital holographic particle image velocimetry was investigated with a lens-based holography configuration. By sampling the chirp signal in the center lobe completely and undersampling the chirp signal in the second- and higher-order lobes by a magnified virtual recording plane produced by an imaging camera lens, the field of view is expanded. Simulation results show that the three-dimensional (3D) location and size of the relatively large particle can be reconstructed with good accuracy. A digital holographic particle image velocimetry system was established for coal particle flow field diagnostics. Compared with the lensless configuration, the field of view of the digital holography system was enlarged 1.9 times, up to 2.78 cm × 2.78 cm × 3 cm. The 3D location, size distribution, and the 3D vector field of coal powder were obtained. The results show that the application of digital in-line holography to measure large particle flow field is feasible.

Measurement of microchannel flow with digital holographic microscopy by integrated nearest neighbor and cross-correlation particle pairing.

A micro digital in-line holographic particle tracking velocimetry (micro-DHPTV) system has been developed and applied to investigate the three-dimensional flow field in straight and Y-junction microchannels. The micro-DHPTV system comprises a cooled frame-transfer CCD camera and a double-pulsed laser. The processing algorithm introduced to evaluate the three-dimensional velocity is based on the combination of integrated cross-correlation and nearest neighbor matching algorithms, taking advantage of information from both the reconstructed particle field and the original holograms fringes patterns. Tests on simulated pairs of holograms show that the particles can be detected, located, and paired with high probability and accuracy. Results obtained in the straight and Y-junction microchannels show that the superimposed vector field is physically reasonable.

Fluoxetine and Ketamine Reverse the Depressive but Not Anxiety Behavior Induced by Lesion of Cholinergic Neurons in the Horizontal Limb of the Diagonal Band of Broca in Male Rat.

The basal forebrain cholinergic system is involved in cognitive processes, but the role of the basal forebrain cholinergic system in depression is unknown. We investigated whether a lesion of cholinergic neurons in the horizontal limb of the diagonal band of Broca (HDB) produces depressive-like behavior and whether fluoxetine or ketamine inhibits such depressive-like behaviors. Here, in rats, we used 192 IgG-saporin to eliminate the cholinergic neurons of the HDB and evaluated depressive-like behaviors using a preference test for sucrose solution and the forced swimming test. Fourteen days after the injection of 192 IgG-saporin into the HDB, the rats exhibited a significantly fewer number of choline acetyltransferase positive cell density in HDB, accompanied with neuronal loss in the entire hippocampus. Meanwhile, these rats significantly reduced preference for sucrose solution, increased immobility time in the forced swimming test, reduced locomotor activity, decreased context dependent memory in fear conditioning and the time spent in the open arms of the plus-maze. A single dose of ketamine (10 mg/kg) increased the sucrose solution consumption, reduced the immobility time in the forced swim test (FST), and increased locomotor activity compared to vehicle-treated rats. Moreover, in rats that were continuously treated with fluoxetine (10 mg/kg/day for 11 days), the sucrose solution consumption increased, the immobility time in the FST decreased, and locomotor activity increased compared to vehicle-treated rats. The present results demonstrate that a lesion of HDB cholinergic neurons results in depressive-like and anxiety-like behaviors and that antidepressants such as fluoxetine or ketamine, can reverse these depressive-like behaviors but not anxiety-like behaviors, and suggest that a lesion of HDB cholinergic neurons and followed hippocampus damage may be involved in the pathogenesis of depression.

Valsartan lowers brain beta-amyloid protein levels and improves spatial learning in a mouse model of Alzheimer disease.

Recent epidemiological evidence suggests that some antihypertensive medications may reduce the risk for Alzheimer disease (AD). We screened 55 clinically prescribed antihypertensive medications for AD-modifying activity using primary cortico-hippocampal neuron cultures generated from the Tg2576 AD mouse model. These agents represent all drug classes used for hypertension pharmacotherapy. We identified 7 candidate antihypertensive agents that significantly reduced AD-type beta-amyloid protein (Abeta) accumulation. Through in vitro studies, we found that only 1 of the candidate drugs, valsartan, was capable of attenuating oligomerization of Abeta peptides into high-molecular-weight (HMW) oligomeric peptides, known to be involved in cognitive deterioration. We found that preventive treatment of Tg2576 mice with valsartan significantly reduced AD-type neuropathology and the content of soluble HMW extracellular oligomeric Abeta peptides in the brain. Most importantly, valsartan administration also attenuated the development of Abeta-mediated cognitive deterioration, even when delivered at a dose about 2-fold lower than that used for hypertension treatment in humans. These preclinical studies suggest that certain antihypertensive drugs may have AD-modifying activity and may protect against progressive Abeta-related memory deficits in subjects with AD or in those at high risk of developing AD.

The effects of humidity and ammonia on the chemical composition of secondary aerosols from toluene/NOx photo-oxidation.

The secondary aerosol formation mechanism in the presence of ammonia (NH3), is poorly understood, especially under high relative humidity (RH) conditions. In this study, a total of seven experiments were conducted from toluene/NOx photo-oxidation in the presence/absence of NH3 under dry (~7% RH) and wet (>60% RH) conditions in a ~3 m3 smog chamber. A series of instruments including gas analysers, scanning mobility particle sizer (SMPS), aerosol mass spectrometry (HR-ToF-AMS) etc. were applied to measure the NOx and O3 concentrations, the mass concentration and chemical composition of secondary aerosol. It was found that NH3 could enhance the mass loading of secondary aerosol, especially under wet condition. However, the presence of NH3 or increasing RH did not have a significant influence on SOA yield. The organic aerosol mass spectrum from AMS showed that the most abundant fragment was at m/z = 44, which was mainly from the fragmentation of carboxylic acids. Compared to the absence of NH3, the fraction of fragment at m/z = 44 and O:C was higher in the presence of NH3, regardless of dry or wet conditions. The highest O:C value of 0.71-0.75 was observed in the presence of NH3 under wet condition, suggesting there could be a synergetic effect between the high RH and the presence of NH3, which jointly contributed to the photochemical aging process of SOA. The N:C increased in the presence of NH3 under both dry and wet conditions, which might be attributed to the carboxylates and organic nitrates formed from the reaction between NH3 and carboxylic acids. The results implied that SOA modelling should consider the role of NH3 and water vapour, which might fill the gap of O:C between laboratory studies and field measurements.

Grape-derived polyphenolics prevent Abeta oligomerization and attenuate cognitive deterioration in a mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive impairments in memory and cognition. Extracellular accumulation of soluble high-molecular-weight (HMW) Abeta oligomers has been proposed to be largely responsible for AD dementia and memory deficits in the Tg2576 mice, a model of AD. In this study, we found that a naturally derived grape seed polyphenolic extract can significantly inhibit amyloid beta-protein aggregation into high-molecular-weight oligomers in vitro. When orally administered to Tg2576 mice, this polyphenolic preparation significantly attenuates AD-type cognitive deterioration coincidentally with reduced HMW soluble oligomeric Abeta in the brain. Our study suggests that grape seed-derived polyphenolics may be useful agents to prevent or treat AD.

Climate change impacts on the potential distribution of Eogystia hippophaecolus in China.

BACKGROUND: Seabuckthorn carpenter moth, Eogystia hippophaecolus (Hua, Chou, Fang, & Chen, 1990), is the most important boring pest of sea buckthorn (Hippophae rhamnoides L.) in the northwest of China. It is responsible for the death of large areas of H. rhamnoides forest, seriously affecting the ecological environment and economic development in north-western China. To clarify the potential distribution of E. hippophaecolus in China, the present study used the CLIMEX 4.0.0 model to project the potential distribution of the pest using historical climate data (1981-2010) and simulated future climate data (2011-2100) for China. RESULTS: Under historical climate condition, E. hippophaecolus would be found to be distributed mainly between 27° N-51° N and 74° E-134° E, with favorable and highly favorable habitats accounting for 35.2% of the total potential distribution. Under future climate conditions, E. hippophaecolus would be distributed mainly between 27° N-53° N and 74° E-134° E, with the possibility of moving in a northwest direction. Under these conditions, the proportion of the total area providing a favorable and highly favorable habitat may decrease to about 33%. CONCLUSION: These results will help to identify the impact of climate change on the potential distribution of E. hippophaecolus, thereby providing a theoretical basis for monitoring and early forecasting of pest outbreaks. © 2018 Society of Chemical Industry.